The present invention relates to endoscopic pickup means incorporating pickup members to be inserted into the inside of an object to be examined and acting to provide an optical image at that portion and to convert the image photoelectrically. It relates also to an endoscopic pickup means equipped with an electromagnetic shield for preventing external electrical or magnetic effects on the pickup members in the pickup means.
Recently, there have been widely available endoscopic pickup means for observing the inside of an object to be examined by inserting the distal end thereof into the inside of the object. Such known endoscopic pickup means include those endoscopes equipped at a tip portion thereof with a pickup members for providing an optical image and for converting the image photoelectrically. The distal end portion acts as a detector end as shown in a prior art embodiment in FIG. 1 as follows:
A ultrasonic scanner 1, pickup means 2 and photoconductive fibre tube 3 are installed in a container 4 at the distal end portion to pickup an ultrasonic tomographic and optical image of the object. Such pickup means 2 are composed of an optical lens 6, solid state image pickup element 7 and preamplifier 8 and are installed in a container defined by electromagnetic shield casing 9 and lead glass plate 10. Such endoscopic pickup means are used frequently together with various other means. For example, the means are used together with an electric knife for surgical operations. Such an electric knife uses a high frequency electric current of from 500 Khz to 5 MHz and consumes power from 50 to 300 W under a source voltage of from 1,000 to 1,200 V. When the endoscopic pickup means are used in combination with an electric knife supplied with a high frequency current, the high frequency current flows into the pickup means even in the presence of minor electrostatic capacity of such a means. Although the pickup means 2 prevents external electric or magnetic effects by means of the container 4 and electromagnetic shield casing 9 in the detector end, as shown in FIG. 1, such shielding is only effective with respect to the side or back side of the solid state image pickup element 7 in the pickup means 2 but is ineffective with respect to the direction of optical lens, i.e. with respect to the optical axis. Hence, when an electric knife and endoscopic pickup means are used together, noise emanating from the electric knife may often interfere detrimentally with the functioning of the detector end of the endoscopic pickup means and may even damage the semiconductors such as the solid state image pickup element 7 incorporated in the endoscopic pickup means. In particular, when the electrodes of the electric knife and solid state image pickup element 7 coexist in the same endoscopic pickup means, both should be isolated or shielded completely. The use of solid state image pickup element 7, i.e. optical pickup means, necessitates an optical passage for passing light. Such an optical passage should be shielded sufficiently.